First synthesis of P-chirogenic prophosphatranes

Syntheses are reported for the novel P-chirogenic bicyclic prophosphatranes P(RNCH₂CH₂)₂N(OCH₂CH₂)—(8) in which the two R groups [i.e., 1-methylenenaphthyl and 1,2-methoxybenzyl (8)] and in its corresponding phosphine oxide (9) are different. Also synthesized was the transannulated protonated phosphatrane cation in the salt [HP(RNCH₂CH₂)₃N]Cl in which the three R groups [i.e., 1-methylenenaphthyl, 1,2-methoxybenzyl, and (S)-1-phenethyl (14)] are different, and also in its corresponding deprotonated prophosphatrane form P(RNCH₂CH₂)₃N (15). Good analytical resolution of racemic 9 is reported, whereas only partial resolution was achieved for diastereomeric 14.     

Polymer-mounted N3P(MeNCH2CH2)3N: a green, efficient and recyclable catalyst for room-temperature transesterifications and amidations of unactivated esters

Merrifield resin-supported N₃P(MeNCH₂CH₂)₃N shows excellent activity in the transesterification of higher esters such as glyceryl tribenzoate to methyl esters. The catalyst was successfully cycled 20 times (albeit with an increase in reaction time) without compromising yield up to the 20th cycle. The catalyst also showed good performance in amidation reactions of unactivated esters with amino alcohols.     

A two-sided Arnoldi algorithm with stopping criterion and MIMO selection procedure

In this paper we introduce a two-sided Arnoldi method for the reduction of high order linear systems and we propose useful extensions, first of all a stopping criterion to find a suitable order for the reduced model and secondly, a selection procedure to significantly improve the performance in the multi-input multi-output (MIMO) case. One application is in micro-electro-mechanical systems (MEMS). We consider a thermo-electric micro thruster model, and a comparison between the commonly used Arnoldi algorithm and the two-sided Arnoldi is performed.     

The synthesis of 2,6,7‐trioxa‐1,4‐diphosphabicyclo[2.2.2]octane revisited: the synthesis of 2,6,7‐triphenyl‐2N,6N,7N‐triaza‐1,4‐diphosphabicyclo[2.2.2]octane and the synthesis of 1λ5‐phosphiranol

We report herein a reliable synthesis of P(OCH₂)₃P in a study aimed at understanding the factors that control its formation. We also report the serendipitous synthesis of the novel phosphiranol (CH₂)₂PO₂H and the synthesis of P(PhNCH₂)₃P in good yield. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:114–117, 2001     

Electron‐rich O=PR3 compounds: Catalysts for alcohol silylation

The catalytic effect of a group of R₃P=O compounds was studied in a mild procedure for the silylation of primary alcohols, secondary alcohols, hindered secondary alcohols, and of hindered phenols in the presence of t‐butyldimethylsilyl chloride (TBDMSCl) and t‐butyldiphenylsilyl chloride (TBDPSCl). It was found that R₃P=O is an efficient catalyst in such reactions when R is a good electron‐donating group, such as Me₂N or n‐Bu and as an NMe(CH₂) moiety in N(CH₂CH₂NMe)₃P=O ( 3 ). However, R₃P=O is a weak or ineffective catalyst when R is a poor electron‐donating group, such as Ph or O‐n‐Bu or as a CH₂N‐o‐CH₂C₅H₄N moiety in N(CH₂CH₂N‐o‐CH₂C₅H₄N)₃P=O. Compound 3 , synthesized by oxidation of commercially available N(CH₂CH₂NMe)₃P, displayed the best catalytic properties for alcohol silylation in terms of efficiency, stability, and safety. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:21–26, 2001